Frances, don't you dare give up on her! She's not going to give up on you too. You are one of the best fishkeepers I know, so keep persevering, something will work soon.
I can sort of understand how distraught you must be feeling now though, I'll never forget the day I found my little moor all torn and battered lying in a plant thinking she was gone.
If she is coming right and still had her appetite then these are good signs, it means she's fighting whatever it is and trying to overcome it. Remember, antibiotics won't kick in straightaway, and so it may be likely that things get worse before they begin to improve. If she wants to float upside down for now, let her. She'll build her strength back up. When my panda went through her floating episode, as much ad I hated seeing her stuggling at the top or rolling upside down, it was better to see her resting than trying to fight. She came right by herself eventually.
When you say Ziggi rights herself, is this like my Gilly, where I went to bed with her stuck at the top then she was ok the following morning, or do you mean she can just flip back over?
What's your nitrATE and pH readings again? And have you tested that nasty tap water of yours recently at all? Just wondering if a tiny flucutation in any of these levels might worsen the symptoms in such a sensitive fish.
I know I'm clutching at straws here, but I really want Ziggi to get better for you *hugs* - don't you dare give up!!
Juwel Rio 180 - female black moor & female panda moor
Fluval Roma 125 - male red fantail & female red cap oranda
Eheim 2213 classic canister filter on each tank